hosts/dn42-ildix-service: prepare BGP setup

hosts/dn42-ildix-service/bird.nix

@@ -0,0 +1,62 @@
+{ config, lib, ... }:
+
+{
+  networking.firewall.allowedTCPPorts = [ 179 ];
+
+  # something doesn't work right
+  services.bird2.enable = false;
+  services.bird2.config = ''
+  router id ${(lib.head config.networking.interfaces.ens18.ipv4.addresses).address};
+
+  ipv6 table bgp6;
+
+  protocol static {
+    ipv6 {
+      table bgp6;
+    };
+    route fd81:edb3:71d8::/48 via "lo";
+  }
+
+  protocol kernel {
+    ipv6 {
+      table bgp6;
+      export filter {
+        krt_prefsrc=${(lib.head config.networking.interfaces.lo.ipv6.addresses).address};
+        accept;
+      };
+      import none;
+    };
+  }
+
+  template bgp ildix {
+    local as 4242422953;
+    graceful restart on;
+    source address fd81:edb3:71d8:ffff:2953::1;
+    ipv6 {
+      table bgp6;
+      next hop self;
+      import keep filtered;
+      import filter {
+        if net ~ [fd00::/8{8,64}] then accept;
+        reject;
+      };
+      export filter {
+        if net ~ [fd81:edb3:71d8::/48{48,64}] then accept;
+        reject;
+      };
+    };
+  }
+
+  protocol bgp peer_ildix_clerie from ildix {
+    neighbor fd81:edb3:71d8:ffff::13 as 4242422953;
+  }
+
+  protocol bgp peer_ildix_nex from ildix {
+    neighbor fd81:edb3:71d8:ffff::14 as 4242422953;
+  }
+
+  protocol device {
+    scan time 10;
+  }
+  '';
+}